Nautiluses are cephalopods, like squid and octopuses, except their bony structure is exhibited as an external shell. Unlike squid and octopuses, nautiluses have no suckers. They are also able to retract into their defensive shell and close the hood, which is made from specialised tentacles.
As the last of it's immediate relations, and having been around for hundreds of millions of years, the surviving nautilus species are considered "living fossils".
In order to swim, the nautilus uses water drawn into its shell for jet propulsion. Whilst inside the shell, the water can also be used to adjust the nautiluses buoyancy by filling or emptying the chambers of its shell.
- Nautilus comes from the Greek for "sailor".
- Related to squid and octopuses.
- Considered "living fossils".
- Have been around mostly unchanged for 500 million years.
- Nautilus pompilius is the largest species in the genus reaching 26.8cm in diameter.